U.S. patent number 4,943,053 [Application Number 07/289,587] was granted by the patent office on 1990-07-24 for post-operative knee rehabilitative dynamometer.
Invention is credited to Stephen H. Smith.
United States Patent |
4,943,053 |
Smith |
July 24, 1990 |
Post-operative knee rehabilitative dynamometer
Abstract
A device for measuring changes in human joint strength including
an open cell body of light weight, low density polyurethane foam
body, an air tight flexible skin sealed about the foam body, the
skin including a multilayer vinyl material having an opening to
permit passage of air into and out of the foam body, a hose sealed
about the opening with a rubber seal, one end of the hose extending
into a center portion of the foam body remote from the opening, the
hose channeling air passing in and out of the opening, and a gauge
connected to the hose for measuring the force of air passing
through the hose upon application of force against the foam
body.
Inventors: |
Smith; Stephen H.
(Riegelsville, PA) |
Family
ID: |
23112177 |
Appl.
No.: |
07/289,587 |
Filed: |
December 22, 1988 |
Current U.S.
Class: |
482/121; 482/113;
482/909; 5/648; 601/33 |
Current CPC
Class: |
A63B
21/0085 (20130101); A63B 21/008 (20130101); A63B
2220/56 (20130101); Y10S 482/909 (20130101) |
Current International
Class: |
A63B
21/008 (20060101); A63B 021/02 () |
Field of
Search: |
;272/130,93,135,125,68,DIG.5 ;128/25R,25B,774,779,782
;73/379-381 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Apley; Richard J.
Assistant Examiner: Flaxman; H.
Attorney, Agent or Firm: Quinn; Charles N.
Claims
I claim:
1. A post-operative knee rehabilitative dynamometer comprising:
a. a cylindrically shaped open-cell body of light weight low
density polyurethane foam body;
b. an airtight flexible skin having a thickness of about 10 to
about 22 mils sealed about said foam body, said skin comprising at
least one layer of vinyl material containing rubber based balloons
as a thickening agent, at least one layer of vinyl based paint and
a gloss coat layer, said skin having an opening to permit pasage of
air into and out of said foam body;
c. a hose sealed about said opening with a rubber grommet and
extending into the center of said foam body remote from said
opening, said hose channeling air passing in and out of said
opening;
d. means connected to said hose for measuring the force of air
passing through said hose upon application of knee force against
said foam body, comprising a gauge having an active and passive
marker connected to one end of a coupling member, said coupling
member being surrounded by a flexible foam hand grip and connected
to said hose on its other end.
2. A post-operative knee rehabilitative dynamometer comprising:
a. a cylindrically shaped open-cell body of lightweight, low
density polyurethane foam;
b. an airtight dip moled elastomeric flexible skin having a
thickness of about 10 to about 22 mils molded and sealed about said
foam body, said skin comprising at least one layer of vinyl
material containing rubber based bolloons as a thickening agent, at
least one layer of vinyl based paint and a gloss coat layer, said
skin having an opening to permit passage of air into and out of
said foam body;
c. a hose sealed about said opening with a rubber grommet and
extending into the center of said foam body remote from said
opening without extending completely through said foam body, said
hose being sealed with cement to said foam body along at least a
portion of the length of said hose within said foam body, said hose
channeling air passing in and out of said opening; and
d. means connected to said hose for measuring air pressure passing
through said hose upon application of knee force against said foam
body comprising a gauge having an active and passive marker
connected to one end of a coupling member, said coupling member
being surrounded by a flexible foam hand grip and connected to said
hose on its other end.
3. Apparatus as defined in claim 2, wherein the foam has a density
of 1.8 pounds per cubic foot.
4. Apparatus as defined in claim 2, wherein said foam has a
firmness rating of about 35 to about 45 I.L.D.
5. Apparatus as defined in claim 1, further comprising a cloth
sleeve surrounding said skin.
6. Apparatus as defined in claim 2, wherein said hose comprises PVC
tubing having reinforcement of nylon braids.
7. A post operative knee rehabilitative dynamometer comprising:
a. a cylindrically shaped open-cell body of lightweight, low
density polyurethane foam having a firmness rating of about 35 to
about 45 I.L.D. and a density of 1.8 pounds per cubic foot;
b. an airtight dip molded elastomeric flexible skin comprising a
material selected from the group consisting of (i) at least one
layer of vinyl material containing rubber based balloons as a
thickening agent, at least one layer of vinyl based paint and a
gloss coat layer, (ii) 1,1, 1-trichloromethane, methylene chloride,
petroleum distillates and toluene and (iii) methyl ethyl ketone,
methyl isobutyl ketone, toluol, red 2B pigment, dioctyl phthalate,
isodecyl diphenyl phosphate and polyvinyl chloride copolymer, said
skin having an opening to permit passage of air into and out of
said foam body;
c. a cloth sleeve surrounding at least a portion of said skin;
d. a hose sealed about said opening with a rubber grommet and
extending into the center of said foam body remote from said
opening without extending completely through said foam body, said
hose comprising polyvinyl chloride tubing having reinforcement of
nylon braids and being sealed with cement to said foam body along
at least a portion of the length of said hose within said foam
body, said hose channeling air passing in and out of said
opening;
e. means connected to said hose for measuring air pressure passing
through said hose upon application of knee force against said foam
body comprising a gauge having a brass diaphragm, brass gear
movement, a brass pressure inlet with a restriction orifice, a
scale with a range of 0 to 100 inches of water and an active and
passive marker connected to end of a hollow wooden dowel coupling
member, said coupling member being surrounded by a flexible foam
hand grip and connected to said hose on its other end.
Description
FIELD OF THE INVENTION
This invention relates to apparatus for measuring changes in human
joint strength and particularly relates to apparatus for
facilitating human knee joint rehabilitation through exercise and
measuring changes in human knee joint strength during
post-operative knee rehabilitation.
BACKGROUND OF THE INVENTION
Surgery on the human knee or knee joint nearly always requires
rebuilding of muscular strength in the knee and/or in connective
tissue surrounding the knee. Various methods and apparatus have
been designed to facilitate rehabilitation of knee function. These
typically include knee exercises designed to restore knee strength
to previous or at least acceptable levels.
Most afflictions of the knee joint are exacerbated by weak
quadriceps and hamstring muscles as the pateint begins to favor the
painful joint. This many times initiates a vicious cycle of
increased pain and increased muscle weakness leading to progressive
joint instability. The quadriceps and hamstrings are the dynamic
stabilizers of the knee joint and must be kept at maximum strength
for optimal knee joint function.
Typical rehabilitative methods and programs extend over a period of
time, usually measured in months, to achieve the desired level of
recaptured knee strength. Measurements of knee strength are
periodically taken to determine progress or completion of the
required rehabilitation regimen. It has, therefore, become
necessary to provide apparatus capable of measuring the relative
restored knee joint strength to determine when it is possible or
desirable to discontinue joint muscle strength rehabilitation.
Description of the Prior Art
Prior art known to applicant includes U.S. Pat. Nos. 3,791,375;
3,974,491; 4,286,603; 4,337,780; 4,521,186; and 4,592,371. Of
these, '780 and '371 are believed to be the most relevant with
respect to the invention disclosed and claimed herein.
'780 discloses a muscle testing apparatus and technique wherein an
airtight bag is connected to a pressure responsive device by
flexible tubing. The airtight bag is provided with elastic bands
for attaching the bag and a pressure responsive gauge to the hand
of the user. A second embodiment includes a small airtight bag, a
large airtight bag, a two way valve and a pressure responsive
device, all connected by flexible tubing. The small airtight bag
has elastic bands for attachment to the palm side of one finger.
The larger airtight bag has elastic bands for attachment to the
palm of the user's hand. The user squeezes the airtight bag which
exerts pressure through the tubing, thereby causing a pressure
reading to be displayed on the pressure responsive device/gauge.
'371 discloses a method and apparatus for muscle testing. An air
bag is inflated by pumping air through a connecting hose by a
flexible rubber bulb. A gauge attaches to the air bag by the
flexible hose. To test the strength of a muscle or a set of
muscles, the patient first applies force to the air bag. After
inflating the air bag via a bulb, the applied force is measured by
the gauge by the process being repeated. The gauge readings are
compared to determine differences in muscle strength.
SUMMARY OF THE INVENTION
This invention encompasses apparatus for providing post-operative
rehabilitation for a human knee joint through exercise and for
simultaneously measuring changes in human joint strength, including
an open-cell body of light weight, low density polyurethane foam
and an airtight flexible skin about the foam body. The light weight
low density polyurethane foam having the preferably air tight
flexible skin about the foam provides apparatus for the human to
rehabilitate the knee joint through post-operative therapy by
providing a controlled amount of resistance to flexure and being of
dimensions which are believed to be optimal for the quadricep
setting exercise (which is the cornerstone of therapy for the knee
disorders and knee post-operative rehabiltation).
The compression premitted by the low density polyurethane form
enhances the exercise value when the apparatus is used for therapy.
The skin preferably is dip molded elastomeric material and has at
least one opening to premit passage of air to and from the foam
body. A hose is sealed about the opening with a rubber seal. The
hose is also connected along the length of the hose to the foam
body, extending within the foam body. The hose preferably extends
into a center portion of the foam body, remote from the opening,
thereby channeling air passing in and out of the opening through
the hose. A gauge attaches to the hose for measuring the force of
air passing through the hose upon application of force against the
foam body. The gauge connects to a rigid coupling member, which
connects to the hose.
BRIEF DESCRIPTION OF THE DARWINGS
FIG. 1 is a schematic fron elevational view of apparatus in
accordance with the invention.
FIG. 2 is a schematic front elevational view of a preferred
embodiment of the invention, partially taken in section.
FIG. 3 is a schematic front elevational view of apparatus emboding
aspects of the invention in use.
DESCRIPTION OF THE PREFERRED EMBODIMENTS AND BEST MODE FOR
PRACTICING THE INVENTION
Referring to the drawings in general and to FIGS. 1 and 2 in
particular, apparatus for providing post-operative therapeutic
exercise and for simultaneously measuring changes in human joint
strength during post-operative knee rehabilitation is designated
generally 10. Apparatus 10 includes pillow 12 consisting of a foam
body portion 14 and a flexible outer skin 16. Skin 16 contains an
opening 18 which is capped by and sealed to rubber grommet 20.
Flexible tubing 22 extends inwardly into grommet 20 through grommet
opening 24. Flexible tubing 22 is preferably sealed by cement to
the foam body portion 14 of pillow 12 along the entire length of
flexible tubing 22 which is within foam body 14 of pillow 12. In
practice, flexible tubing 22 preferably extends about 4 inches into
the foam body portion 14 and cement sealing of tubing 22 to foam
body portion 14 is preferably provided along the entirety of the 4
inch tubing length which is with pillow 12.
The other end of flexible tubing 22 extends into bore 28 of a
preferably foam grip member 30. A tubular coupling 32 is located
within an surrounded by foam grip 30. Coupling 32 receives flexible
tubing 22 at its lower end 34 with tubing 22 extending through bore
28. Upper end 36 of coupling 32 receives gauge mount 38 from gauge
40. Gauge mount 38 extends into and is received by the end of
flexible tubing 22. Gauge 40 contains passive pointer 42 and active
pointer 44. A cloth sleeve (not shown) may be placed over or around
pillow 12 for sanitary and/or aesthetic purposes.
Referring to FIG. 2, a preferred embodiment of apparatus 10 is
shown. Skin 16 is preferably created by dip molding, with foam body
portion 14 being dipped into a suitable liquid phase elastomeric
material so that the elastomeric material molds itself to the outer
configuration of foam body portion 14. Foam body 14 consists of an
open cell low density polyurethane.
Flexible tubing 22 extends into foam body 14, preferably to a
middle portion of foam body 14. Although it is possible that
flexible tubing 22 not extend to the middle of foam body 14, such
placement assists in obtaining more accurate and consistent gauge
readings. Additionally, having flexible tubing extending into the
foam body 14 and being cemented along the length that flexible
tubing extends into foam body 14 provides more secure attachment of
flexible tubing 22 to foam body 14.
Referring now to FIGS. 1 and 2 generally, foam body portion 14
preferably consists of a generally cylindrically shaped piece of
open-cell polyurethane foam. It is not necessary that any
particular foam be utilized; however, it is preferred that the foam
have a firmness rating of about 35-45 I.L.D. and a density of
approximately 1.8 lbs/ft.sup.3.
Pillow 12 is preferably about 12 inches long to enable the full
width of the joint to contact the apparatus. The diameter of pillow
12 is most preferably about 4.75 inches to achieve about a 30
degree joint inflection prior to application of downward force by
the joint on pillow 12. Skin layer 16 surrounding foam body 14
preferably is thin, most preferably having a thickness of between
about 10 mils and about 22 mils. Pillow 12 is preferably formed
having its edges, at either end of the cylinder, formed on about
5/8 inch radii.
The elastomeric material used to form skin 16 may be PDC-10
(manufactured by PDI, Inc. of St. Pual, Minnesota) consisting
primarily of 1,1,1-trichloromethane, methylene chloride, petroleum
distillates and toluene. PDC-10 has a low viscosity which enables
it to easily fill pores and holes on the surface of foam body 14.
This achieves the additional benefit of increased mechanical
bonding of the skin to the foam body.
Skin 16 may, alternatively, be Flexabar brand vinyl material
(manufactured by Flexabar Corp. of Northvale, NJ) consisting
primarily of methyl ethyl ketone, methyl isobutyl ketone, toluol,
red 2B pigment, dioctyl phthalate, isodecyl diphenyl phosphate and
polyvinyl chloride copolymer. Skin 16 is most preferably applied by
dipping pillow 12, but may be applied by other methods. Another
preferred form of skin 16 comprises at least one layer of vinyl
material containing rubber based balloons as a thicknening agent,
at least one layer of vinyl based paint and a glass coat layer.
Flexible tubing 22 preferably consists of PVC tubing having
reinforcement of nylon braids. Flexible tubing 22 is preferably
connected to pillow 12 using a flat, washer-shaped Neoprene bushing
or grommet. Foam grip member 30 preferably consists of a smooth
bore sleeve of dip molded vinyl foam. Coupling 32, residing within
foam grip member 30, preferably consists of a hollow wood dowel and
connects to gauge 40 by gauge mount 38.
Gauge 40 preferably has a brass diaphragm, contains an all brass
gear movement and has a brass pressure inlet with a restriction
orifice. The gauge may have a scale range of about 0 to 100 inches
of water or whatever scale range is desired for a particular
application.
Referring now to FIG. 3, apparatus 10 facilitates rehabilitative
exercise of the human knee joint provides improved measurement of
changes in human joint strength during and resulting from
rehabilitation of the joint. The most common joint for
rehabilitation is the knee joint and it is the knee joint to which
the invention is principally directed, although it is well within
the scope of the invention to employ apparatus 10 in rehabilitation
of other joints, such as the elbow, for example.
It is preferred to place apparatus 10 on a flat surface designated
54 in FIG. 3. The joint to be rehabilitated is then placed over the
surface of foam body 12 opposing that in contact with flat surface
54. The preferred angle of joint flex is about 30.degree.. The
patient then grasps foam grip 32 with his or her hand 56 to
facilitate reading pointers 42 and 44 on gauge 40.
The patient then applies downward force, in the direction shown by
arrow A, using the joint being rehabilitated, to foam body 12.
Application of downward force by the knee joint provides
therapeutic exercise and rehabilitation for the knee joint. The
subject can apply such downward force as many times as the subject
likes or as prescribed by the attending physician or other health
professional. Hence, apparatus 10 provides mechanical means for
performing the rehabilitative exercise as well as means of
measurement of the change in strength of the joint and associated
supportive and connective tissue. The dimensions of the apparatus,
set forth above, particularly the diameter of about four and three
quarter inches, have been found to be optimal for the quadricep
setting exercise, which is the cornerstone of therapy for knee
disorders and post-operative knee rehabilitation.
Application of downward force on foam body 12 from above (by the
joint) and simultaneous resistance to downward movement along
surface 54 causes compression force in foam body 12, thereby
compressing foam body 12. Air contained within the open cell
structure of foam 14 is forced outwardly and exits foam body 12 by
way of flexible tube 22. Exiting air then travels there through the
gauge 40. The resulting air pressure within gauge 40 causes active
pointer 42 to move along the face of gauge 40 to produce a
reading.
Release of downward force by the joint releases compressive force
on foam body 12, thereby releasing air pressure within gauge 40,
coupling 32 and flexible tubing 32. Foam body 12 then returns to
its original uncompressed state and volume. Repeated compression
and decompression of foam body 12 enables utilization of passive
pointer 44 to indicate a maximum amount of compressive force,
thereby indicating maximum joint strength achievable during that
rehabilitative session.
The above procedure may be performed repeatedly during the same
rehabilitation session to obtain a range of measurements, and/or
may be repeated periodically to determine changes in joint strength
over time. The device, by providing both therapeutic exercise and
rehabilitative therapy for the knee joint and permitting the
physician or other health professional to monitor the patient's
progress during rehabilitation, enhances the physician's or other
physical therapist's ability to effectively rehabilitate the
injured joint.
* * * * *